FAIRFIELD, CT — In a significant public health alert, Connecticut officials have confirmed the first longhorned tick Connecticut case carrying Ehrlichia chaffeensis, the bacterium responsible for human monocytic ehrlichiosis (HME), marking the first evidence of such infection in recent years. The finding, announced by the Connecticut Agricultural Experiment Station (CAES) and the U.S. Department of Agriculture (USDA), raises concerns about the emerging risks of tick-borne diseases in the state.
The infected longhorned tick (Haemaphysalis longicornis) was collected in Fairfield County, an area where this invasive species has established populations since 2020. Dr. Goudarz Molaei, medical entomologist at CAES and adjunct professor at Yale School of Public Health, called the discovery a “landmark detection,” noting that although longhorned ticks are known to carry pathogens, this is the first time E. chaffeensis has been found in this species within the U.S.
Human monocytic ehrlichiosis presents with flu-like symptoms such as high fever, headaches, muscle aches, and fatigue. If untreated, it can escalate to severe complications including kidney failure or respiratory distress. Previously, the lone star tick (Amblyomma americanum) was considered the primary vector for this illness — but this Connecticut detection suggests the longhorned tick may now play a similar role.
Originally from eastern Asia, the longhorned tick was first identified in the U.S. in 2017 and has since spread to at least 21 states, mostly in the Northeast and mid-Atlantic. Its ability to reproduce asexually allows populations to expand rapidly, threatening both public health and agriculture.
Dr. Molaei urged Connecticut residents to take proactive measures: use EPA-approved tick repellents, wear protective clothing, and conduct tick checks after outdoor activities. He emphasized the need for robust surveillance programs to track the spread of invasive ticks and the diseases they may carry.
Residents experiencing tick bites or symptoms of ehrlichiosis should seek immediate medical care. For more information on tick prevention and surveillance, visit the Connecticut Agricultural Experiment Station’s website or contact your local health department.
